Sweet cherry cultivar named `Royalton`

ABSTRACT

A new and distinct variety of sweet cherry tree which produces large and firm fruit having rich, strong cherry flavor, crisp flesh and which contain large stones of round to round-conic shape. The fruit has exceptionally high levels of soluble solids at ripeness. A seeding of `NY1725`, the tree is particularly characterized as being self-unfertile, late coming into production, but which bears dark, sweet fruit that is resistant to water stress induced cracking. This vigorous tree is of upright branching habit, forms a tall pyramidal figure, and shows resistance to bacterial canker.

This application is a continuation, of application Ser. No. 08/688,776,filed Jul. 31, 1996, now abandoned which is a continuation ofapplication Ser. No. 08/537,148, filed Aug. 21, 1995, which is nowabandoned, which is a continuation of application Ser. No. 08/240,501,filed May 10, 1994, now abandoned, which is a continuation ofapplication Ser. No. 08/022,881, filed Feb. 12, 1993, now abandoned,which is a continuation of application Ser. No. 07/764,573, filed Sep.18, 1991, now abandoned.

BACKGROUND OF THE INVENTION

This invention is a new and distinct cultivar of sweet cherry`Royalton`, which we discovered in a test planting belonging to the NewYork State Agricultural Experiment Station, Cornell University, Geneva,Ontario County, N.Y. This discovery is a product of a cherry breedingresearch program of the New York State Agricultural Experiment Station("Station").

In 1968 open-pollinated seed from unknown male parent source wasgathered from a NY1725 cherry tree growing on `Station` property. Thisseed was given cold treatment to satisfy its stratification requirementalong with other seeds derived from our research. It was planted inResearch Field Number D-1 Row-19, Tree-161 on Station grounds. When thetree resulting from this seed bore fruit in 1975 we selected it becauseit had unique fruit. It was designated NY11390 and grafted in 1976utilizing two different grafting techniques, topworking and nurseryT-budding. One top-worked, grafted tree was constructed by grafting ontoNY5389 which become the interstem. This tree was located in the Stationresearch field designated as Lucey in Row 6, Tree 16 (abbreviated asLR6T16). Three grafted trees resulted from "T" budding onto "Mahaleb "rootstocks in the nursery. These were harvested in 1980 and stored inStation tree storage facilities until the spring of 1981 when they wereplanted in a Station research location designated as Crittenden Number30, Row 7, Trees 25, 26, and 27 (abbreviated as C30R7T25, T26 and T27).The trees located at LR6T16 and C30R7T25 and T26 subsequently fruitedand had research observations taken about their performance on aregular, annual basis, and were identical to one another in allhorticultural respects that were noted by the various technicians andfaculty scientists who took observations on them. The tree located atC30R7T27 died without providing any important evaluation records.C30R7T25 is still alive and in a sufficiently good state of health toafford useful performance evaluation records. Further trees werepropagated by Station technicians in 1984 using plant parts taken fromthe NY 11390 trees located in LR6T16. These trees were planted in thespring of 1986 in a Station research field designated Lucey Number 50,Row 4, Trees 1 through 7. Other `Royalton` trees from our nurserypropagation were distributed during the 1980s to privateorchardist-cooperators for the purpose of testing using a restricteddistribution test agreement. Trees of NY11390, including a few hundredtrees asexually propagated by grafting, in evaluations prior to filingof the patent application herein were consistantly found to betrue-to-type and stable in their horticultural traits. Since the patentapplication was submitted in 1991, vegetative buds of `Royalton` havebeen provided to commercial fruit tree nurseries, and a breeder-inventorherein has seen commercial orchards of `Royalton` and has seen no changein traits from those that were noted in evaluations prior to the patentapplication being submitted.

COMPARISON OF RELATED ART

In all of the test plantings, trees of `Royalton` bore unusually largefruit with excellent fruit quality as judged by experienced researchersand cherry orchardists. These trees were more resistant to water stressinduced fruit cracking and bacterial canker than most other selectionsand cultivars which we tested. Trees of `Royalton` have been slower tostart setting a fruit crop than were many other sorts we had under test.While of questionable value to orchardists, this lack of precocity is adistinguishing feature of `Royalton`. Trees of `Royalton` are morevigorous than most other sorts of cherries that we have had under test.`Royalton` produces a characteristic type of tree habit that we describegenerally as upright and slightly barren of fruiting spurs on wood threeyears old and older. To our knowledge there is no other cultivar whichhas the same combination of tree growth habit and fruit and fruitingcharacteristics as this invention. The reduction in spur numbers reducestotal fruit yield and increases the fruit size, but since cherries arenot thinned by hand or with plant growth regulators, thinningrequirements are not affected. Table 1 shows a comparison of four fruittraits of 29 sweet cherry cultivars and selections including `Royalton`(NY 11390). It is cited from S. K. Brown and M. C. Bourne, 1988.Assessment of components of fruit firmness in selected sweet cherrygenotypes. HortScience 23(5):902-904.

    ______________________________________                                        Cultivar   Flesh    Total     SSC    FRF                                      or Selection                                                                             (N)      (N)       (% Brix)                                                                             (g)                                      ______________________________________                                        Moreau     1.28 a    3.73 ef  14.2 mn                                                                              609 bc                                   NY 6476      1.21 ab                                                                                4.17 bcd                                                                                16.5 fgh                                                                             422 f-j                                Emperor Francis                                                                           1.13 b    4.44 ab  17.4 cde                                                                              550 d                                  Ulster       0.97 c   4.22 bc   19.1 ab                                                                              466 ef                                 NY 3801      0.97 c    3.20 ijk                                                                               13.7 n                                                                               632 ab                                 Rainier      0.95 c   3.91 de   17.0 d-g                                                                             435 f-i                                NY 9801      0.80 d   3.77 ef   18.9 ab                                                                              419 g-k                                NY 1507      0.79 d   4.66 a    19.4 a                                                                               391 ijk                                NY 5929      0.78 d   3.18 ijk                                                                                19.4 a                                                                               342 lm                                 NY 3308      0.78 d   3.21 ij   15.9 hij                                                                             489 c                                  Hudson       0.77 de                                                                                3.90 de   17.7 cd                                                                              569 cd                                 Bing          0.76 de                                                                               3.38 ghi                                                                                19.1 ab                                                                              326 m                                  Schmidt      0.76 de                                                                                3.42 ghi                                                                                18.6 b                                                                               397 h-k                                Cavalier     0.74 def                                                                               3.93 cde                                                                                15.5 jk                                                                              465 ef                                 Van           0.73 def                                                                              2.78 mn   18.9 ab                                                                              436 fgh                                Starkrimson                                                                                0.72 d-g                                                                               3.41 ghi                                                                                14.0 n                                                                               611 bc                                 Royalton     0.69 c-h                                                                               3.05 j-m                                                                                19.4 a                                                                               554 d                                  Sam           0.66 f-j                                                                              3.35 hi   14.9 klm                                                                             658 a                                  Bada          0.63 g-j                                                                              3.56 fgh                                                                                17.3 cde                                                                             430 f-j                                NY 7679      0.62 hij                                                                               3.20 ijk                                                                                17.1 def                                                                             270 n                                  Windsor      0.58 ijk                                                                               2.92 k-n                                                                                15.8 ij                                                                              419 g-k                                Stella       0.55 jkl                                                                               3.21 lj   16.0 hij                                                                             573 cd                                 Victor       0.54 jkl                                                                               3.67 efg                                                                                15.0 kl                                                                              498 e                                  Viva         0.51 klm                                                                               3.13 i-l                                                                                16.9 efg                                                                             386 jkl                                Hedelfingen                                                                                0.49 klm                                                                               2.88 lmn                                                                                14.8 lm                                                                              412 h-k                                Merton Reward                                                                              0.48 lm                                                                                3.03 j-m                                                                                16.4 ghi                                                                             380 kl                                 May Duke     0.43 mn                                                                                2.67 no       17.9 c                                                                           501 c                                  Early Rivers                                                                               0.42 nm                                                                                2.34 p    13.9 n                                                                               460 efg                                Merton Bounty                                                                              0.39 n             17.0 d-gp                                                                              426 f-j                              ______________________________________                                    

NY3308 referred to in Table 1 has been named `Hartland` and is thesubject of plant patent application Ser. No. 08/835,640, and NY 6476referred to in Table 1 has been named `Somerset` and is the subject ofplant patent application Ser. No. 08/876,370.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows typical flowers of `Royalton`.

FIG. 2 shows fruit and pedicels of `Royalton`.

FIG. 3 shows pits of `Royalton`.

FIG. 4 shows fruit clustering of `Royalton`.

FIG. 5 shows the front and back view of two `Royalton` leaves.

DESCRIPTION OF THE INVENTION Pollination

We have conducted experiments to determine the pollination biologyspecifics about `Royalton`. Our experiments took the form of field teststo cover the opening flowers with paper bags and thereby isolate flowersof `Royalton` from bee visitation. Such bagging allowed us tosubsequently apply pollen derived from known sources to the flowerstigmas to determine the specific pollination compatibility group towhich `Royalton` belongs. It is self unfruitful and belongs to Group IIas described by Crane and Brown, 1955 [Sci. Hort. 11:53-5]. Suitableknown pollinator varieties with bloom dates that overlap those of theinstant tree are `Stella`, `Somerset`, `Hartland`, `Bing` and `Napoleon`(synonym is `Royal Ann`). The only known ineffective pollinator withoverlapping bloom date is `Schmidt` which causes `Royalton` to set verypoor crops. The pollinators have to be planted in close enough proximityto work effectively. Most pomologists agree that the distance betweenpollinator and pollinatee should not be more than two or three trees.

Electrophoretic Enzyme Tests

We conducted electrophoretic enzyme tests to determine the presence orabsence of certain specific enzymes. It is positive for Diaphorase(heterozygous), Glucose Phosphate Isomerase (homozygous), Aconitase(heterozygous) and 6 - Glucose Phosphogluconate Dehydrogenase(heterozygous). While other cherry cultivars or genotypes may have thesesame enzyme characteristics we are unaware of any reports of cultivarswhich are the same as `Royalton` in this regard.

Detailed Plant Description

Accompanying figures depict leaves, flowers, fruits and a pit. Thenumeral color specifications employed are those of The RoyalHorticultural Society Colour Chart (1976).

Flowers and Flowering

Flowers (FIG. 1) are born on terminals of spurs on branches which aretwo years old or older but many fewer fruiting spurs exist on three yearold wood than on most other cultivars which we have tested. They arealso born from axillary buds of long shoots laid down the previousgrowing season. Typically, 3 to 5 flowers are produced from terminalspur buds and 3 to 5 flowers are also borne on axillary buds.

Flowers are white, single and have no unusual features that distinguishthem from those of other sweet cherry cultivars. They are structurallytypical of Prunus avium, with a base number of 5 petals and about 25stamens. As indicated in FIG. 1, the diameter of the flowers is about2.5 cm to 3.0 cm when fully expanded. Pedicels are about 2 cm long andof intermediate thickness, about 10 mm. Anthers are yellow 11B andpollen is yellow-orange 15 A. Self pollinations of `Royalton` areunfruitful.

Full bloom dates at Geneva, N.Y. for `Royalton` in 1996, 1997 and 1998averaged about April 29 whereas full bloom dates for `Somerset` for thesame period in Geneva, N.Y. averaged about April 27 while full bloomdates for `Hartland` for the same period in Geneva, N.Y. averaged aboutMay 1. The bloom dates of `Royalton` overlap sufficiently with those of`Somerset` and `Hartland` for effective pollination. The bloom periodvaries greatly by season. In two, unusually hot spring seasons duringthe 1990s, time between 10% bloom and 100% bloom was one day. In coolseasons, the time is four to five days. First bloom on `Royalton` treeswith Mazzard rootstocks is usually in year seven in the orchard aftergraft placement in the nursery when the nursery is located in a climatesuch as that in Geneva, N.Y. where two-year grow-out of nursery trees isnecessary. If the nursery trees are grown in California or otherclimates where one-year grow-out is possible subsequent to dormantseason bench-grafting or spring grafting, one year is subtracted fromthe length of time from graft placement compared to the two-yeargrow-out cases on either Mazzard or more precocious rootstock cultivarssuch as `Gisela 5`.

Fruiting Habit and Fruit

`Royalton` trees which are grafted to the common cherry rootstock,`Mazzard Seedling` (Mazzard), typically do not produce flowers for atleast two growing seasons after orchard planting. Fruit is seldom set ontrees which flower for their first time. It is common for fruit set tobe delayed on `Royalton`/Mazzard trees until the sixth season. Thisslowness to bear flowers and set fruit, termed "lack of precociousness,"is a unique feature of `Royalton` when it is grafted to Mazzard.

The individual fruits of `Royalton` (FIG. 2) are round-oblate, theirskin color at maturity is greyed-purple 187A. Their flesh color is aslightly lighter shade of greyed-purple 187B. As indicated in FIG. 2,the suture of `Royalton` is very slightly indented or else it is nearlyas flat as the opposite non-suture side of the fruit. Fruits are uniformin the slightly oblate horizontal dimension of their two cheeks andquite flat sided on the suture and opposite, non-suture aspects of theirhorizontal dimension. Fruits have a very uniform large size compared tomost other sweet cherry cultivars, usually averaging over 10 grams perfruit. They are about 3 cm diameter wide ×2.8 cm long (stem end topistillate end). The stem cavity of `Royalton` is shallow and wider thanthat of `Hartland` and more closely resembles the `Bing` cultivar inthis aspect of its shape. Pits (FIG. 3) are large, round to round-conic.Pit color is greyed-orange 165D and surface characteristics are oblateshape the same as for `Bing`. FIG. 4 shows a typical cluster of`Royalton` fruit. Fruits resist moisture stress induced cracking in mostseasons. The soluble solids level of `Royalton` fruit usually exceeds19% when they are grown in Geneva, NY. They have a rich, strong cherryflavor. They are firm, about 0.69 Instron units at maturity. They aresomewhat crisp in texture (mouthfeel) at optimum maturity. They have afruit removal force of about 554 grams of pull force. Thus `Royalton`requires applications of plant growth regulators to "loosen" the fruitsif this cultivar is processed with stems off. Since stems-on, processedfruit are highly important to the brining/maraschino industries that use"cocktail cherries", `Royalton`, with its high fruit removal force,would be ideal for this use with respect to stem retention, but yieldpotential is a disadvantage. Ripening days are about 58 after fullbloom. Ripening for `Royalton` is very uniform. Harvest dates for`Royalton` for the years 1996, 1997 and 1998 averaged out to be July 4,compared to June 30 for `Hartland` and July 14 for `Somerset`.

Tree Habit

`Royalton` tree habit is vigorous, upright with few lateral branchesproduced along the proximal portions of ninety percent of the previousseason's growth. This tree habit and branching structure leads to a"leggy" tall pyramid form. The tallest trees seen are on Mazzardrootstocks and to date are 20 feet tall and still growing upwardly. On`Gisela 5` rootstock and `Inmil` rootstock, both of which are amongstthe most dwarfing of commercially available rootstocks for sweetcherries, the trees have topped out at about 14 feet.

Shoots

`Royalton` shoots are long with few lateral branches. They have manylarge lenticels. In the autumn, after cessation of terminal growthextension, the color of the bark at the fourth intenode above theproximal position is Greyed-orange 165A on the side of the stem which iscommonly exposed to direct sunlight. The color of the other side of thestems at the same position is Greyed-brown 199A. These colors contrastto Greyed-orange 165B and Greyed-brown 199B for the Bing cultivar.Current season shoot growth often has characteristic grooves in the wood(bark and xylem) extending back from the terminal bud toward theproximal end for the first 9 to 10 distal bud positions.

Leaves

Leaves of `Royalton` are large (FIG. 5); usually symmetrical; lamellaglabrous and smooth with adaxial lamella surface dark green 137A;abaxial surface yellow-green 148B; and margin coarsely serrate, 3 to 4serrations per cm; glands reniform, base usually 2 cm wide; stipulespresent during early stages of growth but abscissing before fruitharvest season. Petiole 4 to 4.5 cm; leaf poise typically 60 to 80degrees from shoot.

Usefulness

`Royalton` sweet cherry is well suited for production to fulfill freshmarket demands in most commercial cherry sites where we have tested itsperformance. Its large fruit size, high quality, dark, glossy externalappearance and the good tolerance to water stress induced fruit crackingmake it uniquely well suited to some areas of commercial production.`Royalton` fruit are firmer and less prone to bruising during harvestand handling than the `Summit` cultivar, which is the primary competitorfor `Royalton` in the eastern fruit growing districts. It is similar infruit handling characteristics to the `Ulster` and `Kristin` cultivars,but since `Royalton` has larger fruit,it is preferred over `Ulster` and`Kristin` for fresh market uses. `Royalton` as well as `Summit`,`Ulster` and `Kristin` are more prone to fruit bruising than the fruitof `Bing`, which is the standard western USA cultivar. "Freshness" ofthe stem color to remain bright green during shipping and marketing, isperceived by produce buyers to be a key trait for fresh cherry cultivarsto succeed with the chain stores. `Royalton` has a very "fresh" stem andis comparable to the `Bing` cultivar in stem longevity traits. The treeof `Royalton` is not a consistent producer of regular ample croppingwhen evaluated for this trait across many New York orchard sites in anygiven set of five years and compared to `Hartland` and `Somerset`cultivars. The tree of `Royalton` sets moderate crops even in goodcropping years and needs no crop load adjustment to size the fruitadequately. In our field observations of resistance to bacterial canker(caused by certain species of Pseudomonas) we have noted betterresistance in `Royalton` than many cultivars we have tested. `Royalton`is particularly sensitive to a disorder termed `blast` which is resistedby other cultivars of sweet cherries. "Blast" is caused by certainstrains of Pseudomonas that are quite prevalent in New York State and isa condition that refers to the collapse of fruiting spurs soon afterflower emergence due to systemic infections of the flower bud parts andcambial regions of the fruiting spurs. In spite of its irregularcropping pattern and sensitivity to "blast," those orchardists that haveplaced the highest value on the fruit quality and fruit size and goodhandling traits of `Royalton` and who have orchards that are less proneto heavy annual infections of their `Royalton` trees by "blast"-causingbacteria, continue to plant this cultivar.

We claim:
 1. A new and distinct sweet cherry cultivar as hereindescribed and illustrated.